JP2021081129A - duct - Google Patents

Abstract

To provide a duct capable of realizing smooth circulation for fluid and selective transmission for radio waves.SOLUTION: A duct comprises: a cylinder part that extends from the inside of a building or mobile body, and communicates the outside with the inside; a radio wave obstruction inclined surface that is formed on the inner surface of the cylinder part, extends so as to be inclined toward the axial line of the cylinder part as it goes from the outside to the inside in the axial direction of the cylinder part, and reflects radio waves; and a radio wave selection inner peripheral member that has a cylindrical shape of covering the radio wave obstruction inclined surface from the inner peripheral side, and can selectively transmit only radio waves of a specific frequency made incident on the cylinder part.SELECTED DRAWING: Figure 2

Description

The present disclosure relates to ducts.

Buildings and mobile objects such as nuclear power plants, thermal power plants, aircraft, ships, automobiles, etc., in which various electric devices are housed in the room, are provided with ducts that communicate the room with the outside. For example, outside air is taken in and exhausted through the duct. On the other hand, by providing such a duct, external radio waves may inadvertently enter the room. Therefore, an attempt has been made to shield the radio wave by using the techniques described in Patent Documents 1 and 2 below.
Patent Documents 1 and 2 disclose a configuration in which a radio wave absorbing member for absorbing radio waves (radiation noise) that becomes noise is provided on the inner surface of the duct. In this configuration, it is said that the radiation noise that has entered the duct from the outside can be absorbed by the radio wave absorbing member to suppress the radiation noise from entering the room.

Japanese Unexamined Patent Publication No. 2010-14358 Japanese Unexamined Patent Publication No. 2003-300500

However, in the configurations described in Patent Documents 1 and 2, the structure is arranged so as to project inward from the inner peripheral surface of the duct. As a result, the flow of the fluid flowing through the duct is obstructed, which may cause a pressure loss. Further, in the devices of Patent Documents 1 and 2, there is a request that radio waves of all frequencies are absorbed by the radio wave absorbing member, while radio waves of a specific frequency band are transmitted.

The present disclosure has been made to solve the above problems, and an object of the present disclosure is to provide a duct capable of realizing smooth flow of fluid and selective transmission of radio waves.

In order to solve the above problems, the duct according to the present disclosure is formed to extend from the interior of a building or a moving body, and is formed on a tubular portion that communicates the outside with the interior and an inner surface of the tubular portion. A radio wave obstructing inclined surface that inclines and extends toward the axis of the cylinder portion from the outside toward the room in the axial direction of the cylinder portion and reflects radio waves, and the radio wave obstructing inclined surface from the inner peripheral side. It has a tubular shape to cover, and includes a radio wave selection inner peripheral member capable of selectively transmitting only radio waves of a specific frequency incident on the tubular portion.

According to the duct of the present disclosure, smooth flow of fluid and selective transmission of radio waves can be realized.

It is a figure which shows an example of a building and a duct connected to this. It is sectional drawing which shows the structure of the duct which concerns on 1st Embodiment of this disclosure. It is sectional drawing which shows the structure of the duct which concerns on 2nd Embodiment of this disclosure. It is sectional drawing which shows the structure of the duct which concerns on 3rd Embodiment of this disclosure.

<First Embodiment>
(Duct configuration)
Hereinafter, the duct according to the first embodiment of the present disclosure will be described with reference to FIGS. 1 and 2.
As shown in FIG. 1, the duct 1 according to the present embodiment has a tubular portion 3. The tubular portion 3 is formed so as to extend from the interior 2A of the building 2 and communicates the exterior of the building 2 with the interior 2A. Various devices (not shown) that may be affected by radio waves (radiation noise) are arranged in the room 2A of the building 2. The wall portion of the building 2 shields radio waves propagating to the outside of the building 2. The building 2 may be a building of various plants such as a nuclear power plant or a thermal power plant, or may be a residential house, a factory, a warehouse, or the like.

As shown in FIG. 2, the tubular portion 3 includes a tubular portion main body 21, a radio wave blocking portion 22 constituting a radio wave blocking inclined surface 11, and a radio wave selection inner peripheral member 30. The radio wave blocking portion 22 is fixed to the inner peripheral surface 23 of the tubular portion main body 21.

(Structure of radio wave obstruction part)
In the present embodiment, the inner peripheral surface 23 of the tubular portion main body 21 forming the inner surface of the tubular portion 3 is parallel to the axis L1 of the tubular portion 3. The radio wave blocking portion 22 of the present embodiment includes a radio wave blocking inclined surface 11 and a vertical surface 12 forming the inner surface of the tubular portion 3. In the cross section shown in FIG. 2, the radio wave blocking portion 22 is formed in a right triangle whose hypotenuse is the radio wave blocking inclined surface 11.

The radio wave obstructing inclined surface 11 is at least a surface capable of reflecting radio waves. The radio wave obstructing inclined surface 11 is inclined and extends so as to approach the axis L1 of the tubular portion 3 from the outside toward the room 2A in the axial direction of the tubular portion 3. The radio wave obstruction inclined surface 11 is located at intervals with respect to the axis L1 of the cylinder portion 3 so as not to excessively obstruct the air flow in the cylinder portion 3. In the cross section shown in FIG. 2, the radio wave obstructing inclined surface 11 extends linearly. That is, the inclination angle θ1 of the radio wave obstructing inclined surface 11 with respect to the axis L1 of the tubular portion 3 is constant in the axial direction of the tubular portion 3.

The inclination angle θ1 of the radio wave obstruction inclined surface 11 may be at least larger than 0 degrees and smaller than 90 degrees. It is more desirable that the inclination angle θ1 of the radio wave obstruction inclined surface 11 is, for example, 10 degrees or more. Further, it is more desirable that the inclination angle θ1 of the radio wave obstruction inclined surface 11 is, for example, 45 degrees or less.

The vertical surface 12 of the radio wave blocking portion 22 extends in a direction orthogonal to the axis L1 so as to be separated from the axis L1 with respect to one end of the radio wave blocking inclined surface 11 located on the indoor 2A side in the axial direction of the tubular portion 3.

In the present embodiment, the axis L1 of the tubular portion 3 extends linearly. That is, the tubular portion 3 extends linearly. The axis L1 of the tubular portion 3 may be curved, for example. That is, the tubular portion 3 may be curved in a U-shape or an S-shape, for example.

A pair of radio wave obstructing inclined surfaces 11 (radio wave obstructing portions 22) are arranged at positions facing each other in a direction orthogonal to the axis L1 of the tubular portion 3. The pair of radio wave obstructing inclined surfaces 11 are arranged at positions that coincide with each other in the axial direction of the tubular portion 3. Specifically, the lengths of the radio wave obstructing inclined surfaces 11 in the axial direction of the tubular portion 3 are equal to each other between the pair of radio wave obstructing inclined surfaces 11. Further, the positions of both ends of the pair of radio wave blocking inclined surfaces 11 in the axial direction of the tubular portion 3 coincide with each other. In the present embodiment, the inclination angles θ1 of the pair of radio wave obstructing inclined surfaces 11 coincide with each other.
The radio wave obstructing inclined surface 11 may be formed, for example, in the entire circumferential direction of the tubular portion 3.

The pair of radio wave blocking inclined surfaces 11 (radio wave blocking unit 22) may be, for example, one. In the present embodiment, a plurality of pair of radio wave obstructing inclined surfaces 11 are arranged in the axial direction of the tubular portion 3. As shown in FIG. 2, for example, the plurality of pairs of radio wave obstructing inclined surfaces 11 may be arranged at intervals in the axial direction of the tubular portion 3. The inclination angle θ1 of the radio wave obstructing inclined surface 11 and the distance between the radio wave obstructing inclined surface 11 and the axis L1 of the tubular portion 3 are different from each other among the plurality of radio wave obstructing inclined surfaces 11 arranged in the axial direction of the tubular portion 3. However, in this embodiment, they are equal to each other.

The radio wave obstructing unit 22 of the present embodiment is composed of a radio wave absorber that absorbs radio waves. The radio wave absorber is made of a material capable of absorbing radio waves, such as a metal material, a metal oxide material (for example, ferrite), and a conductive polymer material.

In the present embodiment, the pair of radio wave blocking portions 22 forming the pair of radio wave blocking inclined surfaces 11 are integrally formed. The pair of radio wave blocking portions 22 forming the pair of radio wave blocking inclined surfaces 11 are connected to each other by a connecting portion (not shown), or the radio wave blocking portion 22 is formed over the entire circumferential direction of the tubular portion main body 21. It is formed integrally. The pair of radio wave blocking portions 22 may be formed separately, for example.

(Structure of radio wave selection inner peripheral member)
A radio wave selection inner peripheral member 30 is provided on the inner peripheral side of the radio wave blocking portion 22. The radio wave selection inner peripheral member 30 can selectively transmit only radio waves of a specific frequency. Specifically, as the radio wave selection inner peripheral member 30, a material called Frequency Selective Surface (FSS) is preferably used. The type of FSS is appropriately selected according to the frequency to be transmitted. The radio wave selection inner peripheral member 30 formed of FSS has a cylindrical shape centered on the axis L1. The outer peripheral surface of the radio wave selection inner peripheral member 30 is supported and fixed by the end edge on the inner peripheral side of the radio wave blocking portion 22 described above. Specifically, an embodiment in which the radio wave selection inner peripheral member 30 is adhered and fixed to the radio wave obstructing portion 22 can be considered. The radio wave blocking inclined surface 11 is covered from the inner peripheral side by the radio wave selection inner peripheral member 30.

(Action effect)
According to the duct 1 of the present embodiment, a pair of radio wave obstructing inclined surfaces 11 facing each other in the direction orthogonal to the axis L1 of the tubular portion 3 are arranged at positions that coincide with each other in the axial direction of the tubular portion 3. As a result, it is possible to effectively reduce the invasion of radio waves (radiated noise) into the room 2A through the duct 1. This point will be described below.
For example, as shown in FIG. 2, in the duct 1 of the present embodiment, the radio wave P1 as noise from the outside toward the room 2A inside the tubular portion 3 passes through the radio wave selection inner peripheral member and reaches the radio wave obstructing inclined surface 11. Incident. When reflected by one of the pair of radio wave obstructing inclined surfaces 11, the radio wave P1 tends to face the other radio wave obstructing inclined surface 11. As a result, the radio wave P1 is further reflected by the other radio wave obstructing inclined surface 11, and tends toward the outside side (left side in FIG. 2) of the duct 1. That is, it is possible to suppress the radio wave P from going toward the room 2A in the duct 1. Further, the radio wave P1 can be suitably attenuated by reflecting the radio wave P1 a plurality of times on the pair of radio wave obstructing inclined surfaces 11. As described above, it is possible to effectively reduce the invasion of the radio wave P into the room 2A through the duct 1.
As a result, various devices arranged in the room 2A of the building 2 can be protected from radio waves (radiation noise).

On the other hand, the radio wave P2 of another frequency reflected by the radio wave selection inner peripheral member 30 without passing through the radio wave selection inner peripheral member 30 repeatedly reflects in the extending direction of the tubular portion 3 from one end side of the duct. It reaches the other end side (indoor 2A side). That is, only radio waves of frequencies that are not desired to be blocked can reach the room through the duct.

Further, in the above configuration, since the radio wave selection inner peripheral member 30 is provided on the inner peripheral side, no projecting object is formed on the inner peripheral surface side of the tubular portion 3. As a result, the flow of air or the like that originally flows through the duct 1 can be smoothly circulated while suppressing the pressure loss. As a result, smooth flow of fluid and selective transmission of radio waves can be realized at the same time.

Further, according to the duct 1 of the present embodiment, the radio wave obstruction portion 22 constituting the radio wave obstruction inclined surface 11 is fixed to the inner peripheral surface 23 of the cylinder portion main body 21 extending parallel to the axis L1 of the cylinder portion 3. Will be done. Therefore, the radio wave obstructing inclined surface 11 can be easily formed on the duct 1 (cylinder main body 21) that does not have the radio wave obstructing inclined surface 11.

Further, according to the duct 1 of the present embodiment, the radio wave obstructing unit 22 is composed of a radio wave absorber. Therefore, the radio wave can be absorbed as well as reflected by the radio wave obstructing unit 22. That is, the radio wave that has entered the duct 1 from the outside can be more effectively attenuated by the radio wave obstructing unit 22. Therefore, it is possible to more effectively reduce the invasion of radio waves into the room 2A through the duct 1.

Further, according to the duct 1 of the present embodiment, the pair of radio wave obstructing portions 22 constituting the pair of radio wave obstructing inclined surfaces 11 are integrally formed. Therefore, when the pair of radio wave obstructing portions 22 are provided on the inner peripheral surface 23 of the tubular portion main body 21, it is possible to reliably prevent the pair of radio wave obstructing inclined surfaces 11 from being displaced from each other in the axial direction of the tubular portion 3. .. That is, when the pair of radio wave obstructing portions 22 are provided on the inner peripheral surface 23 of the tubular portion main body 21, the relative positioning of the pair of radio wave obstructing inclined surfaces 11 can be easily performed.

Further, according to the duct 1 of the present embodiment, a plurality of pair of radio wave obstructing inclined surfaces 11 are arranged in the axial direction of the tubular portion 3. Therefore, even if the radio wave from the outside toward the room 2A in the duct 1 is not reflected by the pair of radio wave obstructing inclined surfaces 11 located on the outside side, it is reflected by another radio wave obstructing inclined surface 11 located on the indoor 2A side. be able to. As a result, it is possible to further reduce the invasion of radio waves into the room 2A.

Further, according to the duct 1 of the present embodiment, the radio wave obstructing inclined surface 11 extending in the axial direction of the tubular portion 3 so as to approach the axis L1 of the tubular portion 3 from the outside toward the room 2A is the tubular portion. It is located at intervals with respect to the axis L1 of 3. Further, the inclination angle θ1 of the radio wave obstruction inclined surface 11 is smaller than 90 degrees. Therefore, it is possible to suppress the occurrence of turbulence in the air flow in the tubular portion 3 and suppress the pressure loss of the air flow in the tubular portion 3 to be small. In particular, the pressure loss of the air flow flowing from the outside side toward the room 2A side in the cylinder portion 3 can be suppressed to a small value. When the inclination angle θ1 of the radio wave obstructing inclined surface 11 is 45 degrees or less, the occurrence of turbulence in the air flow in the tubular portion 3 is further suppressed, and the pressure loss of the air flow is further suppressed. Can be done.

<Second embodiment>
Subsequently, the second embodiment of the present disclosure will be described with reference to FIG. The same components as those in the first embodiment are designated by the same reference numerals, and detailed description thereof will be omitted. As shown in the figure, in the duct 1B according to the present embodiment, the accommodating recess 40 is formed on the inner peripheral surface 23B of the tubular portion main body 21B, and the radio wave obstructing portion 22 similar to that described above is formed in the accommodating recess 40. Is housed. Specifically, the accommodating recess 40 has a rectangular cross-sectional shape that is recessed from the inner peripheral surface 23B of the tubular portion main body 21B toward the outer peripheral side. The depth of the accommodating recess 40 (that is, the radial dimension with respect to the axis L1) is set to be slightly larger than the height dimension of the radio wave obstructing portion 22.

Further, the accommodating recess 40 is covered from the inner peripheral side by the radio wave selection inner peripheral member 30B. Further, the inner peripheral surface 31B of the radio wave selection inner peripheral member 30B and the inner peripheral surface 23B of the tubular portion main body 21B are flush with each other. It should be noted that these surfaces do not have to be completely flush with each other, and a slight error is allowed as long as it is intended that a step is not substantially formed.

According to the above configuration, the radio wave obstructing inclined surface 11 is housed in the accommodating recess 40, and the accommodating recess 40 is further covered from the inner peripheral side by the radio wave selection inner peripheral member 30B. Therefore, no protrusion is formed on the inner peripheral surface 23B side of the duct 1B (cylinder main body 21B). As a result, the flow of air or the like that originally flows through the duct 1B can be smoothly circulated while suppressing the pressure loss.

Further, according to the above configuration, since the inner peripheral surface 23B of the tubular portion main body 21B and the inner peripheral surface 31B of the radio wave selection inner peripheral member 30B are flush with each other, the flow of air or the like flowing through the duct 1B is pressured. It can be distributed more smoothly while suppressing loss.

<Third Embodiment>
Next, the third embodiment of the present disclosure will be described with reference to FIG. The same components as those in the above embodiments are designated by the same reference numerals, and detailed description thereof will be omitted. As shown in the figure, the duct 1C according to the present embodiment further includes a reinforcing member 50 in addition to the respective configurations described in the first embodiment. The reinforcing member 50 is provided for the purpose of reinforcing the radio wave selection inner peripheral member 30C. The reinforcing member 50 has a tubular shape that covers the radio wave selection inner peripheral member 30C from the outer peripheral side. The inner peripheral surface of the reinforcing member 50 is in contact with the outer peripheral surface of the radio wave selection inner peripheral member 30C without a gap. That is, the inner diameter dimension of the reinforcing member 50 is set to the same value as or slightly larger than the outer diameter dimension of the radio wave selection inner peripheral member 30C. As the reinforcing member 50, a metal mesh is preferably used. The outer peripheral surface of the reinforcing member 50 is supported and fixed to the inner peripheral edge of the radio wave blocking portion 22 by an adhesive or the like.

According to the above configuration, in addition to the same effects as those described in the first embodiment described above, the durability of the duct is further enhanced by reinforcing the radio wave selection inner peripheral member 30C with the reinforcing member 50. Can be done.

(Other embodiments)
Although each embodiment of the present disclosure has been described in detail with reference to the drawings, the specific configuration is not limited to this embodiment and includes design changes and the like within a range not deviating from the gist of the present disclosure. .. For example, it is possible to adopt a configuration further including a honeycomb shield provided in the opening on the outer side of the tubular portion 3 (3B, 3C). The honeycomb shield is formed by forming a large number of through holes in a plate material capable of reflecting radio waves. When the duct of the present invention includes a honeycomb shield, it is possible to prevent radio waves from entering the tubular portion, so that it is possible to more effectively reduce radio waves from entering the room through the duct. Further, for example, a honeycomb shield provided in the opening on the outer side of the tubular portion 3 may be further provided. The honeycomb shield is formed by forming a large number of through holes in a plate material capable of reflecting radio waves. According to this configuration, it is possible to more effectively reduce the invasion of radio waves into the room through the duct 1. Further, the tubular portion 3 may be formed so as to extend from the interior of a moving body such as an aircraft or an automobile.

<Additional notes>
The duct described in each embodiment is grasped as follows, for example.

(1) The duct 1 according to the first aspect is formed to extend from the interior of a building or a moving body, and is formed on a tubular portion 3 that communicates the outside with the indoor 2A and an inner surface of the tubular portion 3. A radio wave obstruction inclined surface 11 that inclines and extends toward the axis L1 of the cylinder 3 from the outside in the axial direction of the cylinder 3 and reflects radio waves, and the radio wave obstruction inclination. It has a tubular shape that covers the surface 11 from the inner peripheral side, and includes a radio wave selection inner peripheral member 30 capable of selectively transmitting only radio waves of a specific frequency incident on the tubular portion 3.

According to the above configuration, the radio wave of a specific frequency passes through the radio wave selection inner peripheral member 30 and is incident on the radio wave obstructing inclined surface 11. When the radio wave is reflected by one of the pair of radio wave obstructing inclined surfaces 11, the radio wave is likely to go toward the other radio wave obstructing inclined surface 11. As a result, the radio wave is further reflected on the other radio wave obstructing inclined surface 11, and tends to go toward the outside of the duct 1. That is, it is possible to suppress the radio waves from going into the room through the duct 1. Further, the radio wave can be suitably attenuated by reflecting the radio wave a plurality of times on the pair of radio wave obstructing inclined surfaces 11.
On the other hand, radio waves of other frequencies reflected by the radio wave selection inner peripheral member 30 without passing through the radio wave selection inner peripheral member 30 are repeatedly reflected in the extending direction of the duct 1, and are reflected from one end side of the duct 1 to the other. Reach the end side. That is, only radio waves having a frequency that is not desired to be blocked can reach the room 2A through the duct 1.
Further, in the above configuration, since the radio wave selection inner peripheral member 30 is provided on the inner peripheral side, no projecting object is formed on the inner peripheral surface 23 side of the duct 1. As a result, the flow of air or the like that originally flows through the duct 1 can be smoothly circulated while suppressing the pressure loss.

(2) In the duct 1B according to the second aspect, the tubular portion 3B is formed with an accommodating recess 40 recessed from the inner peripheral surface of the tubular portion 3 to the outer peripheral side, and the radio wave obstructing inclined surface 11 is the accommodating recess 40. The radio wave selection inner peripheral member 30B extends from the inner peripheral surface of the recess 40 and is accommodated in the accommodating recess 40, and covers the accommodating recess 40 from the inner peripheral side.

According to the above configuration, the radio wave obstructing inclined surface 11 is housed in the accommodating recess 40, and the accommodating recess 40 is further covered from the inner peripheral side by the radio wave selection inner peripheral member 30B. Therefore, no protrusion is formed on the inner peripheral surface 23B side of the duct 1B. As a result, the flow of air or the like that originally flows through the duct 1B can be smoothly circulated while suppressing the pressure loss.

(3) In the duct 1B according to the third aspect, the inner peripheral surface 23B of the tubular portion 3B and the inner peripheral surface 31B of the radio wave selection inner peripheral member 30B are flush with each other.

According to the above configuration, since the inner peripheral surface 23B of the tubular portion 3B and the inner peripheral surface 31B of the radio wave selection inner peripheral member 30B are flush with each other, the flow of air or the like flowing through the duct 1B can be suppressed from pressure loss. However, it can be distributed more smoothly.

(4) The duct 1C according to the fourth aspect has a tubular shape that covers the radio wave selection inner peripheral member 30C from the outer peripheral side, and further has a reinforcing member 50 that reinforces the radio wave selection inner peripheral member 30C.

According to the above configuration, the durability of the duct 1C can be further enhanced by reinforcing the radio wave selection inner peripheral member 30C with the reinforcing member 50.

(5) In the duct 1 (1B, 1C) according to the fifth aspect, the radio wave obstructing inclined surfaces 11 are arranged in pairs at positions facing each other in the direction orthogonal to the axis L1, and the pair of the radio wave obstructing inclined surfaces are arranged. 11 is arranged at positions that coincide with each other in the axial direction of the tubular portions 3 (3B, 3C).

According to the above configuration, the radio wave obstruction by the radio wave obstruction inclined surface 11 can be realized in a wider range in the direction orthogonal to the axis L1.

(6) In the duct 1 (1B, 1C) according to the sixth aspect, the tubular portion 3 (3B, 3C) has an inner peripheral surface 23 (23B, 23C) parallel to the axis L1. (21B, 21C) and a radio wave blocking portion 22 fixed to the inner peripheral surface 23 (23B, 23C) of the tubular portion main body 21 (21B, 21C) and forming the radio wave blocking inclined surface 11.

According to the above configuration, the radio wave obstructing inclined surface 11 can be easily provided to the duct (cylinder main body 21 (21B, 21C)) that does not have the radio wave obstructing inclined surface 11.

(7) In the duct 1 (1B, 1C) according to the seventh aspect, the radio wave obstructing unit 22 is composed of a radio wave absorber that absorbs radio waves.

According to the above configuration, the radio wave can be absorbed as well as reflected by the radio wave obstructing unit 22. That is, the radio wave that has entered the duct 1 (1B, 1C) from the outside can be more effectively attenuated by the radio wave obstructing unit 22. Therefore, it is possible to more effectively reduce the invasion of radio waves into the room through the duct 1 (1B, 1C).

(8) In the duct 1 (1B, 1C) according to the eighth aspect, the tubular portion 3 (3B, 3C) is the tubular portion main body 21 (21B, 21C) and the tubular portion main body 21 (21B, 21C). The radio wave obstructing unit 22 is fixed to the inner peripheral surface 23 (23B, 23C) of the above and constitutes the radio wave obstructing inclined surface 11, and the radio wave obstructing unit 22 is composed of a radio wave absorber that absorbs radio waves. There is.

According to the above configuration, the radio wave can be absorbed as well as reflected by the radio wave obstructing unit 22. That is, the radio wave that has entered the duct 1 (1B, 1C) from the outside can be more effectively attenuated by the radio wave obstructing unit 22. Therefore, it is possible to more effectively reduce the invasion of radio waves into the room through the duct 1 (1B, 1C).

(9) In the duct 1 (1B, 1C) according to the ninth aspect, a plurality of the pair of the radio wave obstructing inclined surfaces 11 are arranged in the axial direction.

According to the above configuration, the radio waves from the outside toward the room 2A inside the cylinder 3 (3B, 3C) are located on the room 2A side even if they are not reflected by the pair of radio wave obstructing inclined surfaces 11 located on the outside side. It can be reflected on another radio wave obstructing inclined surface 11. As a result, it is possible to further reduce the invasion of radio waves into the room 2A.

(Radio wave selection inner circumference member)
1,1B, 1C Duct 2 Building 2A Indoor 3,3B, 3C Cylinder 11 Radio wave obstruction inclined surface 21,21B, 21C Cylinder body 22 Radio obstruction 23, 23B, 23C (Cylinder body) Inner peripheral surface 30 , 30B, 30C Radio wave selection inner peripheral member 31 (of radio wave selection inner circumference member) Inner peripheral surface 40 Storage recess 50 Reinforcing member L1 Axis line θ1 Inclination angle of radio wave inhibition inclined surface 11

Claims (9)

A tubular portion that extends from the interior of a building or mobile body and communicates the exterior with the interior.
A radio wave obstructing inclined surface formed on the inner surface of the tubular portion, extending in an axial direction of the tubular portion from the outside toward the room, and extending toward the axis of the tubular portion to reflect radio waves.
A radio wave selection inner peripheral member having a tubular shape that covers the radio wave obstructing inclined surface from the inner peripheral side and capable of selectively transmitting only radio waves of a specific frequency incident on the tubular portion.
Duct with. The tubular portion is formed with a housing recess recessed from the inner peripheral surface of the tubular portion to the outer peripheral side.
The radio wave obstructing inclined surface extends from the inner peripheral surface of the accommodating recess and is accommodated in the accommodating recess.
The duct according to claim 1, wherein the radio wave selection inner peripheral member covers the accommodating recess from the inner peripheral side. The duct according to claim 2, wherein the inner peripheral surface of the tubular portion and the inner peripheral surface of the radio wave selection inner peripheral member are flush with each other. The duct according to any one of claims 1 to 3, which has a tubular shape that covers the radio wave selection inner peripheral member from the outer peripheral side, and further has a reinforcing member that reinforces the radio wave selection inner peripheral member. The radio wave obstructing inclined surfaces are arranged in pairs at positions facing each other in a direction orthogonal to the axis.
The duct according to any one of claims 1 to 4, wherein the pair of radio wave obstructing inclined surfaces are arranged at positions corresponding to each other in the axial direction of the tubular portion. The cylinder part
A tubular body having an inner peripheral surface parallel to the axis, and
A radio wave obstructing portion fixed to the inner peripheral surface of the tubular portion main body and forming the radio wave obstructing inclined surface, and a radio wave obstructing portion.
The duct according to any one of claims 1 to 5. The duct according to claim 6, wherein the radio wave obstructing unit is composed of a radio wave absorber that absorbs radio waves. The cylinder part
With the main body of the cylinder
The radio wave obstructing portion fixed to the inner peripheral surface of the tubular portion main body and forming the radio wave obstructing inclined surface, and the radio wave obstructing portion
With
The duct according to any one of claims 1 to 7, wherein the radio wave obstructing unit is composed of a radio wave absorber that absorbs radio waves. The duct according to any one of claims 1 to 8, wherein a plurality of the pair of radio wave obstructing inclined surfaces are arranged in the axial direction.

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